In vehicle wheel bearing apparatus that supports a wheel of a vehicle, such as an automobile, it is conventional to mount a brake rotor on a wheel mounting flange of a wheel hub together with a wheel. The mounting of the brake rotor on the wheel mounting flange is usually carried out by an automobile manufacturer to which the wheel bearing apparatus are delivered. Recently, the wheel bearing apparatus is delivered to the automobile manufacturer after the brake rotors have been temporarily mounted on the wheel mounting flange of the bearing apparatus by a bearing manufacturer. In such a case, the brake rotor is usually delivered to the automobile manufacturer being screwed onto the wheel mounting flange.
However, according to such a temporary mounting method where screws are used, not only are screws required for the temporal mounting but threaded apertures are required for the temporary mounting screws on both the brake rotor and the wheel mounting flange. This reduces the manufacturing efficiency and increases time and work for the temporal mounting. Thus, the manufacturing cost increases since the temporary mounting screws have to be screwed into both the threaded apertures of the brake rotor and the wheel mounting flange after having aligning the threaded apertures.
FIG. 9 is one example of a wheel mounting apparatus of the prior art. The wheel bearing apparatus 50 includes an inner member 54 with a wheel hub 52 and an inner ring 53. The wheel hub 52 is integrally formed with a wheel mounting flange 51 at its one end for mounting a wheel (not shown). The wheel hub 52 has one inner raceway surface 52a on its outer circumference. A cylindrical portion 52b axially extends from the inner raceway surface 52a. A serration 52c is formed on its inner circumference for torque transmission purposes. The inner ring 53 is formed with the other inner raceway surface 53a on its outer circumference. An outer member 55 is integrally formed on its outer circumference with a flange 55b that is to be mounted on a body (not shown) of a vehicle. The outer member inner circumference includes double row outer raceway surfaces 55a, 55a. Double row balls 57, 57 are rollably held equidistantly between the inner and outer raceway surfaces by cages 56, 56. A plurality of hub bolts 58 are securely mounted on the wheel mounting flange 51 equidistantly along the flange periphery. The inner ring 53 is axially immovably secured on the wheel hub 52 by a caulked portion 52d. The caulked portion 52d is formed by plastically deforming the end of the cylindrical portion 52b radially outward.
Seals 59, 60 are arranged on both ends of the outer member 55. The seals 59, 60 seal annular spaces formed between the inner and outer members 54, 55. The seals 59, 60 prevent leakage of lubricating grease contained within the bearing and the entry of rain water or dust into the bearing from the outside.
In such a wheel bearing apparatus, a through aperture 51a is formed on the wheel mounting flange 51 of the wheel hub 52. Pins 61, each forming a projecting portion, are press-fit and insert into apertures 62a, each forming an insert portion, formed on the brake rotor 62. The brake rotor 62 can be temporally mounted on the wheel mounting flange 51 by inserting the forward ends of the pins 61 into the insert apertures 62a. Thus, this prevents the rotor from coming off the wheel mounting flange 51. Accordingly, the wheel bearing apparatus 50, with the brake rotor 62 temporarily mounted on the wheel mounting flange 51, can be simply obtained in a short time by positioning the insert apertures 62a of the brake rotor 62 oppositely to the pins 61. The brake rotor 62 is pushed against the wheel mounting flange 51. See, Japanese Laid-open Patent Publication No. 069746/2007.
However, in the prior art wheel bearing apparatus 50, problems exist. It is believed that a rotational balance of the wheel hub 52 would be upset when the number of the pins 61 does not correspond to the number of hub bolts 58. It is believed that the wheel mounting flange 51 would be deformed when the pins 61 are press-fit into the through apertures 51a of the wheel mounting flange 51. Thus, the accuracy of the surface run-out of the outer side surface 51b of the wheel mounting flange 51, on which the brake rotor 62 is laid, would be reduced. This results in the generation of brake judder. It is believed that the brake rotor 62 would be lifted and thus come out from the wheel mounting flange 51 if a shearing force is applied to the pins 61 by the brake rotor 62. This occurs when the chamfered tip end 61a of any pin 61 does not perfectly projected from the outer side surface of the brake rotor 62 and remains in the insert aperture 62a. It is believed that any pin 61 would be broken when a shearing force is applied to the pin 61 by the brake rotor 62 during driving of a vehicle.